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Kronos AV
Kronos AV
JE Audio
JE Audio was found in Hong Kong on 2007 by John Lam. The company has a strong commitment to design and manufacture the finest quality audio electronics. Our dedication to lifelike reproduction of music has led to many technical innovations, awards and great reviews. We are proud to be different. We have our own idea about what is imperative and how things should be done. We are obsessive about details, and would go the extra mile to develop new audio amplifying topologies and to select the most suitable components for the applications.

JE Audio Dyad S400 Hybrid Power Amplifier
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  • Regular price £13,499.00
  • Available Worldwide Shipping

Dyad S400 is a state-of-the-art true fully balanced hybrid power amplifier in which voltage amplification is done by all vacuum tubes. S400 employs the patented Dual Balanced Feedback Topology (DBFT) and proprietary high current buffer amplifier (HCBA). The design of S400 is highlighted in the following diagram.

Since there are two out-of-phase signals in a fully balanced amplifier, two HCBAs are used for the output stage. Each HCBA has the following properties:

* Unity voltage gain
* High speed and high current gain
* High power capacity
* Input and output are maintained at DC ground level automatically
* Protect output for over current, output DC offset and overheat
* Stable with and without global feedback applying to it

One HCBA amplifies signal of one phase and the other HCBA amplifies signal of the opposite phase. Since the input stage and second stage use all vacuum tubes for signal amplification, and the HCBAs have unity voltage gain, the overall sound has retained very much to what we expect from a tube power amplifier. But it has advantage over vacuum tube power amplifier in terms of high current drive provided by the semiconductor buffer amplifier at the output. The fully balanced hybrid power amplifier eliminates a frequency dependent and bulky output transformer altogether. Finally, a fully balanced amplifier has an additional advantage of having a strong immunity against common mode noises.

Dual Balanced Feedback Topology (DBFT) and high current buffer amplifier (HCBA).
  • Fully balanced input (also has separate RCA input).
  • Fully balanced output (no loudspeaker terminal is connected to a ground terminal).
  • Patented Dual Balanced Feedback Topology (DBFT) improves signal linearity and audio fidelity.
  • Signal amplification is handled by all vacuum tubes.
  • Output current amplification is handled by all solid-state MOSFET high current buffer amplifier (HCBA) output stage.
  • HCBA output stage is protected for over current, DC offset and over heat.
  • The S400 continuously monitors the vacuum tubes and the solid-state transistors packed HCBA. If a vacuum tube is operated outside of its allowable operation region, or any HCBA is detected with over current, high DC offset voltage or over heat, a LED lamp will turn to red. And the S400 will shut down automatically.
  • Audio grade low noise toroid power transformer is used.
  • Audio grade signal capacitors are used for signal coupling.
  • Soft-start circuit reduces the inrush current when switching on. It also ensures that in the first 45 seconds the vacuum tubes can warm up properly. This prolongs life of all rectifying diodes, power supply filtering capacitors and vacuum tubes.

We are still delivering orders as normal. When your order ships you will still receive tracking details. For UK shipments, Our couriers have procedures in place to ensure deliveries are arriving as quickly & safely as possible. Drivers can now sign for your parcels, however will notify you that they have arrived, in order to ensure you receive your parcel. Signing for the parcel has now been stopped temporally for hygiene reasons. Drivers are also working with customer instructions, so you can ask them to leave the parcel in a safe place (doorstep etc...) if you prefer not to come into direct contact with the driver.

There has been no changes to deliveries with Brexit. All deliveries to the UK mainland, Northern Ireland and the Republic of Ireland are operating as normal. No VAT or charges are applicable. 

Express Deliveries

Express Delivery is FREE on all orders over £50. Express Delivery offers delivery in 24-72 hours from time of purchase. We use premium couriers for this service, mainly DPD & Royal Mail. DPD will offer you a one hour window for delivery to make sure someone is at home, or you can reschedule the delivery if no one is around. 

Standard Deliveries

Here at Kronos AV, we have vast experience with e-commerce sales. Making sure that your parcel arrives undamaged is a huge priority for us. That’s why at Kronos AV, we only use premium couriers for all our orders. All our parcels are shipped with DPD or Royal Mail and are always sent Signed For to make sure it gets to the right person. 

If for any reason your parcel does arrived damaged, please get in touch, and we will be happy to get everything resolved for you. We are always on hand to help!


Delivery is FREE on all orders over £50. In order to offer FREE delivery to UK customers, we use several premium couriers to ensure your delivery arrives safe.

Most large orders (over 2kg) ship using DPD or DHL courier and smaller orders (under 2kg) by Royal Mail signed for services.

The most appropriate courier will be chosen for the items ordered to ensure the quickest possible delivery.

We can offer very generous trade in offers across the majority of our product range. 

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If you have any question, please feel free to call us on 03435236169 or email